1. Field of the Invention
The present invention relates to a vibration-type driving apparatus such as an ultrasonic motor.
2. Description of the Related Art
A vibration-type driving apparatus (linear ultrasonic motor), as disclosed in Japanese Patent Laid-Open No. 2004-304887, has been proposed in the related art as a linear ultrasonic motor that linearly drives an object.
The principle of driving the foregoing linear ultrasonic motor will be described using FIGS. 4A, 4B-1, and 4B-2.
As shown in the external perspective view of a linear ultrasonic motor 510 in FIG. 4A, the linear ultrasonic motor 510 is constituted by a vibrating body 501, a driven body 506, and a pressing member (not shown) for pressing the vibrating body 501 to the driven body 506.
The vibrating body 501 is constituted by a piezoelectric element 505 serving as an electro-mechanical energy conversion element, a rectangular elastic body 502 joined to one side of the piezoelectric element 505 to form a single unit, and two protrusions 503 and 504 formed on the upper surface of the elastic body 502.
In ultrasonic motors, vibrations in a plurality of desired vibration modes are excited by applying a voltage with a particular frequency to a piezoelectric element, and the vibration modes are overlapped with each other to create a vibration for driving.
For such a vibration, the linear ultrasonic motor 510 in FIG. 4A causes the vibrating body 501 to vibrate in two bending vibration modes shown in FIGS. 4B-1 and 4B-2.
Both of the two bending vibration modes are bending vibration modes in out-of-plane directions of the plate-like vibrating body 501.
One of the vibration modes is a secondary bending vibration mode (Mode-A) in the longitudinal direction of the vibrating body 501, and the other vibration mode is a primary bending vibration mode (Mode-B) in the lateral direction of the vibrating body 501.
The shape of the vibrating body 501 is designed so that the resonance frequencies of the two vibration modes match or are close to each other.
The protrusions 503 and 504 are disposed at the positions of nodes of a vibration in Mode-A or in the vicinity thereof. Since protrusion end faces 503-1 and 504-1 swing with their disposed positions as the fulcrum due to the vibration in Mode-A, they reciprocate in the X-direction.
Furthermore, the protrusions 503 and 504 are disposed at the position of an antinode of a vibration in Mode-B or in the vicinity thereof. The protrusion end faces 503-1 and 504-1 reciprocate in the Z-direction due to the vibration in Mode-B.
By exciting vibrations in the two vibration modes (Mode-A and Mode-B) at the same time and overlapping them so that the phase difference therebetween reach the vicinity of ±π/2, the protrusion end faces 503-1 and 504-1 move in an elliptical orbit in the X-Z plane.
This elliptical motion allows the driven body 506 that is in pressure-contact with the vibrating body 501 to be driven in one direction.
In the foregoing related-art vibration-type driving apparatus (linear ultrasonic motor), a known configuration for applying a voltage to the piezoelectric element uses a flexible printed board.
Specifically, the configuration is such that a plurality of electrodes are provided on one side of the piezoelectric element, and a driving signal is applied to the plurality of electrodes from a driving control unit (not shown) via the flexible printed board.
The flexible printed board is bonded to the piezoelectric element with an adhesive.